etcd-operator no longer works

etcd-operator was deprecated two years ago, and does not seem to still work with newer versions of k8s. Installing gives me this error:

```
helm install stable/etcd-operator --generate-name
WARNING: This chart is deprecated
Error: INSTALLATION FAILED: failed to install CRD crds/etcd-cluster-crd.yaml: resource mapping not found for name: "etcdclusters.etcd.database.coreos.com" namespace: "" from "": no matches for kind "CustomResourceDefinition" in version "apiextensions.k8s.io/v1beta1"
ensure CRDs are installed first
```